CLASSIFICATION OF IGNEOUS ROCKS 227 



EiCHSTADT.^ Valbellite consists of bronzite, olivine, and brown 

 hornblende in variable amounts, with accessory magnetite, green 

 spinel, and pyrrhotite. The magnetite may be very abundant. 

 Olivinite covers a group of rocks of varying composition. Essen- 

 tially they contain olivine with augite and hornblende. Anorthite 

 may be present in some occurrences, but in general it is rare. 

 Another rock belonging here is Saitzew's^ hornblende-diallage- 

 peridotite from the Koswinski-Kamenj, in the Urals, later described 

 by Duparc and Pearce^ under the name koswite. This rock con- 

 sists of much diopside, less olivine and less hornblende in a cement 

 of magnetite, giving a sideronitic texture. Chrome spinel is also 

 present. The main characteristic is the texture, which, the authors 

 say, passes to that of ordinary peridotite by a decrease in the 

 amount of magnetite. The sideronitic texture is not confined to 

 these dikes, but also occurs in other magnetite-rich peridotites. 



Families 4 and 11. — This group includes the olivine-pyroxene 

 (both orthorhombic an^ monoclinic) rocks. Among them are 

 IherzoHte de Lametherie,'' named from the original locality of 

 Lherz, in the Pyrenees, and consisting of olivine, enstatite, and 

 diopside, with accessory picotite. In other localities the pyroxene 

 is diopside and bronzite, and chromite may be present in small 

 amounts. 



Diallage-peridotite Kloos^ consists of diallage, olivine, and some 

 chromite. 



Wehrlite is a name given by von Kobell,^ in 1834, to a rock from 

 Wehrle in Hungary, under the impression that it was a mineral. 



^Fr. Eichstadt, "Pyroxen och amfibolforande bergarter fran mellersta och ostra 

 Smaland," Bihang till Kongl. Svenska Vetenskaps-Akademiens Handlmgar, XI, No. 14 

 (1887), pp. 95, 123. 



^ A. Saitzew, "Geologische Untersuchungen im Nikolai-Pawdinschen Kreise und 

 Umgebung, im Gebiete des Central-Ural und dessen ostlichen Abhang," Mem. Com. 

 Geol., XIII, No. I (1892), p. 91. 



3L. Duparc and F. Pearce, "Sur la koswite, une novella pyroxenite de I'Oural," 

 Comples Rendus, CXXXII (1901), 892-94. 



'• De Lametherie, Theorie de la terre, II, 281; also Leqons mineralogique, II, 206. 



5 J. H. Kloos, "tjber Uralit und die strukturellen Verschiedenheiten der Horn- 

 blende in einigen Gesteinen des Schwarz- und Odenwaldes," 55 Vers, deiitsch. Naturf. 

 u. Arze (Strassburg, 1885); also "Studien im Granitgebiet des siidl. Schwarzwaldes," 

 Neues Jahrh., Ill (1884), 146. 



' Franz von Kobell, Geschichte der Miner alogie (Miinchen, 1864), p. 660. 



